/rust/registry/src/index.crates.io-1949cf8c6b5b557f/pic-scale-safe-0.1.12/src/math/bartlett.rs
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1 | | /* |
2 | | * Copyright (c) Radzivon Bartoshyk, 10/2024. All rights reserved. |
3 | | * |
4 | | * Redistribution and use in source and binary forms, with or without modification, |
5 | | * are permitted provided that the following conditions are met: |
6 | | * |
7 | | * 1. Redistributions of source code must retain the above copyright notice, this |
8 | | * list of conditions and the following disclaimer. |
9 | | * |
10 | | * 2. Redistributions in binary form must reproduce the above copyright notice, |
11 | | * this list of conditions and the following disclaimer in the documentation |
12 | | * and/or other materials provided with the distribution. |
13 | | * |
14 | | * 3. Neither the name of the copyright holder nor the names of its |
15 | | * contributors may be used to endorse or promote products derived from |
16 | | * this software without specific prior written permission. |
17 | | * |
18 | | * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" |
19 | | * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
20 | | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE |
21 | | * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE |
22 | | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
23 | | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR |
24 | | * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER |
25 | | * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, |
26 | | * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
27 | | * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
28 | | */ |
29 | | |
30 | | use crate::math::consts::ConstPI; |
31 | | use num_traits::{AsPrimitive, Float}; |
32 | | use std::ops::{Mul, Sub}; |
33 | | |
34 | | #[inline(always)] |
35 | 0 | pub(crate) fn bartlett<V: Copy + Sub<Output = V> + Mul<Output = V> + 'static + PartialOrd>( |
36 | 0 | x: V, |
37 | 0 | ) -> V |
38 | 0 | where |
39 | 0 | f32: AsPrimitive<V>, |
40 | | { |
41 | 0 | let x = if x < 0f32.as_() { 0f32.as_() - x } else { x }; |
42 | 0 | if x > 2f32.as_() { |
43 | 0 | return 0f32.as_(); |
44 | 0 | } |
45 | 0 | 1f32.as_() - 0.5f32.as_() * x |
46 | 0 | } |
47 | | |
48 | | #[inline(always)] |
49 | 0 | pub(crate) fn bartlett_hann< |
50 | 0 | V: Copy + Sub<Output = V> + Mul<Output = V> + Float + ConstPI + 'static, |
51 | 0 | >( |
52 | 0 | x: V, |
53 | 0 | ) -> V |
54 | 0 | where |
55 | 0 | f32: AsPrimitive<V>, |
56 | | { |
57 | 0 | let x = x.abs(); |
58 | 0 | if x > 2f32.as_() { |
59 | 0 | return 0f32.as_(); |
60 | 0 | } |
61 | 0 | let l = 2.0f32.as_(); |
62 | 0 | let fac = x / (l + l); |
63 | 0 | 0.62f32.as_() - 0.48f32.as_() * fac + 0.38f32.as_() * (2f32.as_() * V::const_pi() * fac).cos() |
64 | 0 | } |
65 | | |
66 | | #[cfg(test)] |
67 | | mod tests { |
68 | | use super::*; |
69 | | |
70 | | #[test] |
71 | | fn bartlett_is_triangle_over_support() { |
72 | | assert_eq!(bartlett(0f32), 1f32); |
73 | | assert_eq!(bartlett(1f32), 0.5f32); |
74 | | assert_eq!(bartlett(-1f32), 0.5f32); |
75 | | assert_eq!(bartlett(2f32), 0f32); |
76 | | assert_eq!(bartlett(2.5f32), 0f32); |
77 | | } |
78 | | |
79 | | #[test] |
80 | | fn bartlett_hann_peaks_at_center_and_decays_to_zero() { |
81 | | assert!((bartlett_hann(0f32) - 1f32).abs() < 1e-6); |
82 | | assert!(bartlett_hann(2f32).abs() < 1e-6); |
83 | | assert!(bartlett_hann(-2f32).abs() < 1e-6); |
84 | | assert_eq!(bartlett_hann(2.5f32), 0f32); |
85 | | assert!((bartlett_hann(1f32) - bartlett_hann(-1f32)).abs() < 1e-6); |
86 | | } |
87 | | } |